Downhole Electromagnetic Telemetry System Utilizing Electrically Insulating Material and Related Methods

ABSTRACT

A downhole electromagnetic telemetry system and method whereby electrically insulating material is placed above and/or below an electrical current launching device or receiver along a well string in order to extend the range of the telemetry system, increase the telemetry rate, and/or reduce downhole power requirements.

FIELD OF THE INVENTION

The present invention relates generally to electromagnetic telemetryand, more specifically, to a downhole telemetry system in whichelectrically insulating material is placed around one or more portionsof a well string in order to extend the range of the telemetry system,increase the telemetry rate, and/or reduce downhole power requirements.

BACKGROUND

Electromagnetic telemetry systems are used in downhole operations totransmit and receive electromagnetic signals for a variety of purposes.An electromagnetic telemetry transmitter launches an electrical signalinto drill pipe either by impressing a potential difference across asection of drill collar connected to the drill pipe or by launching acurrent on the drill string by way of a toroid that is placed around asection of the drill string.

However, when an electromagnetic transmitter is within casing, signallosses can be excessive as the current on the pipe jumps to the casing,thus launching part of the signal to the casing, but also shorting partof the signal along the casing. Furthermore, and especially when thereis direct contact between any part of the pipe and the casing, motion ofthe drill string can cause intermittent contact and, thus, introduce avery significant noise into the telemetry signal. Moreover, as thesignal travels up or down the pipe and/or casing, it is attenuatedsubstantially as current leaks into the formation surrounding theborehole. As a result, the signal received at the surface or downholereceiver can be attenuated to the point where the signal to noise ratiois not high enough to allow for reliable communication, even at a datarate of a few bits per second.

In view of the foregoing, there is a need in the art for a costeffective method by which to extend the range of the telemetry systemand/or to prevent short circuits through the mud and into the casing ordirectly into the casing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate a drilling rig and an electromagnetictelemetry system 10 according to one or more exemplary embodiments ofthe present invention; and

FIGS. 2A, 2B and 2C are graphs illustrating the signal improvementeffects of adding electrically insulating material above and/or belowthe current launching device, according to one or more exemplaryembodiments of the present invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments and related methodologies of the presentinvention are described below as they might be employed in a downholetelemetry system in which electrically insulating material is placedaround one or more portions of the well string. In the interest ofclarity, not all features of an actual implementation or methodology aredescribed in this specification. Also, the “exemplary” embodimentsdescribed herein refer to examples of the present invention. It will ofcourse be appreciated that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure. Further aspects andadvantages of the various embodiments and related methodologies of theinvention will become apparent from consideration of the followingdescription and drawings.

As described herein, exemplary embodiments of the present inventionextend the range of an electromagnetic telemetry system when the systemis within a cased or uncased section of a well. To achieve thisobjective, electrically insulating material is applied to the wellstring immediately above and/or immediately below the electrical currentlaunching device (gap sub assembly or toroid, for example) or receiver.In other embodiments, the electrically insulating material may alsocover the current launching device or receiver. Accordingly, as thecurrent launching device launches the electrical signal into the drillpipe, the electrically insulating material prevents the current fromjumping to the casing either directly or through the drilling mud, thuspreventing or reducing the severity of short circuits through the casingand/or electrical current leakage into the formation in situations wherecasing is not present around the transmitter, thereby improving therange and/or signal to noise ratio of the telemetry system, and/orreducing the power required by the system. Moreover, in thoseembodiments where a downhole receiver is utilized, the electricallyinsulating material acts to reduce current leakage from the well stringto the casing or formation during downlink operations.

In certain exemplary embodiments, the electrically insulating materialis one or more sheets of material wrapped around the bottom holeassembly or drill pipe using an adhesive backing. In others, forexample, electrically insulating swellable material or a variety ofcoatings may also be utilized. As a result, the range of theelectromagnetic telemetry system within and without the cased section isincreased by roughly the same amount of pipe that is electricallyinsulated. Therefore, the data rate of the electromagnetic telemetrysystem may also be increased without the need for adding repeaters.

FIGS. 1A and 1B illustrate a drilling rig 12 and an electromagnetictelemetry system 10 according to one or more exemplary embodiments ofthe present invention. As understood in the art, electromagnetictelemetry system 10 generates and/or receives electromagnetic wavesdownhole. Electromagnetic telemetry system 10 includes a bottom holeassembly 14, current launching device 16 (gap sub assembly, for example)and tubular section 18 (referred to in combination as a well string, forexample), all extending down through casing 20 of well 22. The term“well string,” as used herein, may refer to a variety of deploymentstrings such as, for example, drill string, coiled tubing, productiontubing, etc. In the exemplary embodiment of FIGS. 1A and 1B, the wellstring is a drill string.

In addition, electromagnetic telemetry system 10 includes a receiver 24electrically coupled to a ground reference 26, and may also have one ormore repeaters (not shown) along tubular 18 as necessary. In general,electromagnetic telemetry system 10 communicates by launching a lowfrequency current (between about 1 and 30 Hz, for example) along tubular18. Signals associated with the current are then detected at the surfaceby receiver 24 where a potential difference is measured between drillingrig 12 and ground 26. In this exemplary embodiment, electromagnetictelemetry system 10 may operate in, for example, a phase modulatedcarrier mode, pulse position modulation mode or orthogonalfrequency-division multiplexing mode, or a number of other modulationmodes, as will be understood by those ordinarily skilled in the arthaving the benefit of this disclosure.

In order to produce the current transmitted by electromagnetic telemetrysystem 10, electrical current launching device 16 is provided adjacentbottom hole assembly 14 (or may form part of bottom hole assembly 14).In a first exemplary embodiment, electrical current launching device 16is provided as an electrical break between bottom hole assembly 14 andtubular 18 which effectively turns the well string into a large antenna.In the exemplary embodiment of FIG. 1A, a gap sub assembly serves as theelectrical break or antenna. An electrical potential difference isthereby created between bottom hole assembly 14 and tubular 18, thuscreating the transmitted current. As understood in the art, the gap subassembly is an electrical isolation joint designed to withstand the hightorsional, bending, tensile and compression loads of electromagnetictelemetry system 10. However, in other embodiments, electrical currentlaunching device 16 may instead be a toroid assembly, as understood inthe art. These and other aspects of electromagnetic telemetry system 10will be readily understood by those ordinarily skilled in the art havingthe benefit of this disclosure.

Still referring to FIGS. 1A and 1B, tubular 18 has been lowered throughblow out preventer 28 down into well 22, and through casing 20. Aspreviously mentioned, in this exemplary embodiment, tubular 18 is drillpipe forming part of a drill string; however, in other embodiments,tubular 18 may be, for example, coiled or production tubing utilized forsome other operation. Nevertheless, tubular 18 extends down to currentlaunching device 16 which is coupled to bottom hole assembly 14. A drillbit 30 is positioned at the distal end of bottom hole assembly 14. Drillbit 30 may be rotated by a variety of methods including, for example,tubular 18 or a mud motor. In this exemplary embodiment, bottom holeassembly 14 comprises a CPU (not shown) and electromagnetic telemetrytransmitter 32 that includes electronics necessary to sense, detect andtransmit electromagnetic signals via current launching device 16, inaddition to handling other operations of bottom hole assembly 14, asunderstood in the art.

In certain exemplary embodiments of electromagnetic telemetry system 10,an electrically insulating material 34 is applied around one or moreportions of a drill string (tubular 18 or bottom hole assembly 14) aboveand/or below current launching device 16. In one embodiment, theelectrically insulating material 34 need not be a perfect insulator;rather, the resistivity of electrically insulating material 34 is noless than two orders of magnitude higher than that of the fluid(drilling mud, for example) used during the downhole operation.Moreover, in certain embodiments, it is also not necessary thatelectrically insulating material 34 be without break along tubular 18 orbottom hole assembly 14. Nevertheless, electrically insulating material34 may be a variety of materials, such as, for example, a swellablematerial, injection-molded coating, bands, sleeves, stabilizers, highoxygen fuel spray coating, anodized layers, etc. The swellable materialmay be, for example, such materials as used in the Swell Technology™Systems, commercially available through the Assignee of the presentinvention, Halliburton Energy Services, Co. or Houston, Tex. Inaddition, the swellable material may be selected based upon the mud type(oil or water based, for example) such that, once contact has been madewith the drilling mud, the swellable material swells onto bottom holeassembly 14 and/or tubular 18 and adheres to it.

As previously described, electrically insulating material 34 is appliedto one or more portions of the well string (i.e., tubular 18 and bottomhole assembly 14) above and/or below the current launching device 16. Inone embodiment, electrically insulating material 34 is appliedimmediately above and/or below current launching device 16, as shown inFIGS. 1A and 1B. However, in other embodiments, electrically insulatingmaterial 34 may also be placed all along tubular 18 as desired. Incertain exemplary embodiments, electrically insulating material 34 maybe applied as a tape that is wrapped around one or more portions ofbottom hole assembly 14 as it is tripped into well 22. The electricallyinsulating tape may be adhered along the well string by wetting it withthe same fluid (drilling mud, for example) that will be utilized tocause it to swell. However, in other embodiments, an adhesive backingmay also be utilized on the tape to adhere it to the well string.Exemplary insulating tapes may be, for example, swellable materials,adhesive-backed rubber, silicone rubber, Teflon, polyester films,polyimide tapes, polymer sheets (polyethylene, for example). In certainembodiments, however, the use of polyethylene would be limited to about115° C. since a typical melting point for a polyethylene plastic isaround 120° C. Moreover, the tape may be one to several feet wide and afraction of an inch thick (⅛ inch, for example).

In an alternate embodiment, electrically insulating material 34 may beformed into a sleeve having an inner diameter somewhat larger than thatof the box-pin outer diameter of bottom hole assembly 14 or tubular 18.In one example, the electrically insulating sleeve would be appliedalong the well string as it is tripped into well 22. The electricallyinsulating sleeve may be held in place during deployment in a variety ofways such as, for example, by applying clamps or tape to hold theelectrically insulating sleeve in place until the swellable materialbegins to swell. In the alternative, the electrically insulating sleevemay be snug enough around the well string portion to hold itself inplace until swelling begins. In addition, portions of the electricallyinsulating sleeve may be wetted with drilling mud, thus causing thatportion of the sleeve to swell and adhere to the well string.Nevertheless, after deployment, as the electrically insulating sleevecomes into the contact with the drilling fluid, the swellable materialis then activated to swell against the surface of bottom hole assembly14 or tubular 18, thus adhering to it. The swellable material may beselected, for example, based upon the type of drilling mud utilized, aswill be understood by those ordinarily skilled in the art having thebenefit of this disclosure.

Moreover, still referring to FIGS. 1A and 1B, electrically insulatingmaterial 34 may also be applied to one or more sections of tubular 18using any of the methods described herein. Such an embodiment willminimize current loss during transmission along tubular 18. In prior arttelemetry systems, the current traveling up the well string and casingtends to migrate off the well string/casing and go to ground, thusresulting in signal loss. However, through use of this alternateembodiment of the present invention whereby one or more portions oftubular 18 are insulated above current launching device 16, the amountof current going to ground along tubular 18 is then reduced, whichincreases the amount of current traveling back up the well string andreaching the surface, thus resulting in a larger amplitude signal. Incertain embodiments, electrically insulating material 34 may be utilizedalong bottom hole assembly 14 only, tubular 18 only, or in combinationalong both bottom hole assembly 14 and tubular 18.

Additionally, in yet another alternative embodiment, an electricallyresistive fluid may be pumped into well 22 to assist in electricallyisolating electromagnetic telemetry system from casing 22. Such fluidmay be drill mud and or fluid additives added to the fluid. In anotherembodiment, the electrically resistive fluid may be utilized withoutelectrically insulating material 34, as will be understood by thoseordinarily skilled in the art having the benefit of this disclosure.

Although not shown in FIGS. 1A and 1B, exemplary embodiments of presentinvention may also be utilized in downlink telemetry systems which mayonly utilize a downhole receiver. As understood in the art,electromagnetic telemetry system 10 may comprise a receiver in place ofcurrent launching device 16 which is used to receive signals transmittedfrom the surface via tubular 18. Such an embodiment may or may notinclude electromagnetic telemetry transmitter 32. In such embodiments,the receiver may be, for example, a gap sub assembly or toroid aspreviously described. However, unlike the previous embodiments describedherein, the receiver will instead receive and decode the signal in orderto perform some operation within bottom hole assembly 14. In suchembodiments, placement of electrically insulating material 34 around oneor more portions of tubular 18 will reduce and/or eliminate currentleakage from tubular 18 into casing 20 or the open hole formation, aswill be understood by those ordinarily skilled in the art having thebenefit of this disclosure.

Now with reference to the graphs of FIGS. 2A-2C, the signal improvementeffects of adding electrically insulating material 34 above and/or belowcurrent launching device 16 will now be described. The graphs plot thecurrent on tubular 18 and casing 20 along various depths of well 22wherein various lengths of electrically insulating material 34 have beenapplied. FIG. 2A is a plot of the current on tubular 18 and casing 20 ina 2,800 foot well with 2,500 feet of drill pipe, 2,500 feet of casing, a1 inch gap sub assembly, at a depth of 1400 feet and using 0.25 ohmmeter mud. As can be seen, the current very rapidly bleeds off of thepipe into casing 20 in such a way that a significant portion of thecurrent is no longer available as a signal, but instead has beeneffectively shorted out by casing 20.

FIG. 2B is a plot of the current on tubular 18 and casing 20 in the samewell as FIG. 2A, but with 400 feet of electrically insulating material34 along bottom hole assembly 14 below the 1 inch gap sub assembly. Themud resistivity is again 0.25 ohm meters. As illustrated, current stillquickly bleeds to casing 20 as soon as there is no electricallyinsulating material 34, but the overall signal level is significantlyimproved. FIG. 2C is yet another plot of the current along the well, butwith 400 feet of insulation above and 400 feet of insulation below a 1inch gap sub assembly. The mud resistivity is again 0.25 ohm meters. Asbefore, the current quickly leaks to casing 20 where the electricallyinsulating material 34 ends, but the overall signal level is againimproved. Chart 1 below is a summary of these and other signal levelsthat may be observed at the surface.

CHART I Voltage mv c V dB R mud Insulation to inf dBm Ohm m Inches/feet0.21972 73.1624 0.25 1″ 0.33617 69.4688 0.25 100 feet below gap 0.6156164.2139 0.25 400 feet below gap 1.3439 57.433 0.25 800 feet centered ongap 0.33688 69.4505 2.5 1″ 0.43331 67.2641 2.5 100 feet below gap0.71538 62.9092 2.5 400 feet below gap 1.4828 56.5782 2.5 800 feetcentered on gapAs shown, the signal level in millivolts appears in the first column,the signal level expressed as decibel millivolts appears in the secondcolumn, the mud resistivity appears in the third column, and a summaryof the insulation appears in the fourth column. Although the foregoingexamples address embodiments utilizing transmitters, the same types ofgains in signal to noise ratio will be present in embodiments utilizingdownhole receivers, as will be understood by those ordinarily skilled inthe art having the benefit of this disclosure.

In view of the foregoing, electrically insulating material 34 may beapplied to the well string in a variety of ways. For example,electrically insulating material 34 may be applied to one or moreportions of the well string as the well string is being made up. In thealternative, one or more portions of the well string may be insulatedbefore the well string is made up. Moreover, exemplary embodiments ofthe present invention may be utilized in open and cased wells. In casedsections of the well, electrical insulating material 34 reduces orprevents short circuits from current launching device 16 into casing 20.In open sections of the well, electrical insulating material 34 reducesor prevents current leakage from the well string into the formation.Accordingly, the up hole or down hole telemetry range of electromagnetictelemetry system 10 is increased by a distance roughly equal to thelength of insulation applied and downhole power requirements arereduced. Therefore, electromagnetic telemetry is efficiently providedwhile drilling (or performing other operations) with the telemetrytransmitter inside and outside the casing.

In addition, in those embodiments of the present invention utilizedinside cased wells, the portion of the well string below currentlaunching device 16 (or the receiver) may be insulated. However, inthose embodiments utilized along portions of wells that are open to theformation, portions of the well string above current launching device 16(or the receiver) may be insulated. In the latter embodiment, the lengthof one or more electrically conductive portions of the formation alongthe open well may be determined, and the length of electricallyinsulating material 34 is determined based upon the length of theconductive formation. As understood in the art, the location of theelectrically conductive formations may be determined based upon, forexample, resistivity logs of other wells near the well underconstruction, as will be understood by those ordinarily skilled in theart having the benefit of this disclosure. Based upon the logged data,as well as the planned well trajectory and how far the bit will bebeyond the conductive formation at a given time (in those embodimentsutilized in a drill string), those same skilled persons can readilydetermine the length of electrically conductive material necessary to beapplied above current launching device 16 (or the receiver). Forexample, if the well is a vertical well and the bit run is planned toextend to a depth of 12,000 feet, the electromagnetic transmitter is 200feet above the drill bit, and a very conductive formation extends from10,000 to 11,000 feet, then 1,800 feet of electrically insulatingmaterial 34 may be positioned above the current launching device 16 sothat once current launching device 16 passed the bottom of theconductive formation (i.e. once it was beyond a depth of 11,000 feet),there would always be electrically insulating material 34 betweentubular 18 and the formation. Nevertheless, in either embodiment, one ormore portions of the well string above and/or below current launchingdevice 16 or the receiver (not shown) may also be insulated.

An exemplary methodology of the present invention provides a method forutilizing an electromagnetic telemetry system in a downhole well, themethod comprising providing a well string comprising one or moretubulars attached to a bottom hole assembly, the bottom hole assemblycomprising at least one of an electrical current launching device or areceiver; applying electrically insulating material around one or moreportions of the well string; deploying the bottom hole assembly into thewell; conducting an electromagnetic telemetry operation using the bottomhole assembly; and utilizing the electrically insulating material toreduce at least one of short circuits from the current launching deviceto casing or current leakage from the well string into the casing orformation along the well. The conducted electromagnetic telemetryoperation may be, for example, transmitting and/or receivingelectromagnetic signals along the system. Another method furthercomprises applying the electrically insulating material around one ormore portions of the well string immediately above or below the currentlaunching device or receiver. In another method, applying theelectrically insulating material around the one or more portions of thewell string comprises wrapping the one or more portions of the wellstring with one or more sheets of electrically insulating material.

In yet another, applying the electrically insulating material around theone or more portions of the well string comprises positioning aninsulation sleeve around the one or more portions of the well string,the insulation sleeve being comprised of electrically insulatingswellable material. In another, applying the electrically insulatingmaterial around the one or more portions of the well string comprisesapplying at least one of: an electrically insulating swellable material;an electrically insulating injection-molded coating; an electricallyinsulating spray coating; or an electrically insulating anodized layer.In yet another, applying the electrically insulating material around theone or more portions of the well string comprises: determining a lengthof an electrically conductive portion of the formation along the well;and applying the electrically insulating material based upon thedetermined length.

An exemplary embodiment of the present invention provides anelectromagnetic telemetry system for use in a downhole well, the systemcomprising a well string comprising one or more tubulars attached to abottom hole assembly, the bottom hole assembly comprising at least oneof an electrical current launching device or a receiver; andelectrically insulating material positioned around one or more portionsof the well string to reduce at least one of short circuits from thecurrent launching device to casing; or current leakage from the wellstring into the casing or formation along the well. In anotherembodiment, the electrically insulating material is positionedimmediately above or below the current launching device or receiver. Inyet another, the electrical current launching device is a gap subassembly or a toroid. In another, the receiver is a gap sub assembly ora toroid. In another, the electrically insulating material is one ormore sheets of electrically insulating material. In yet another, theelectrically insulating material is an insulation sleeve. In another,the electrically insulating material is at least one of: an electricallyinsulating swellable material; an electrically insulatinginjection-molded coating; an electrically insulating spray coating; oran electrically insulating anodized layer.

Yet another exemplary methodology of the present invention provides amethod for utilizing an electromagnetic telemetry system in a downholewell, the method comprising: applying electrically insulating materialaround one or more portions of a well string comprising at least one ofan electrical current launching device or a receiver; deploying the wellstring into the well; and utilizing the electrically insulating materialto reduce at least one of short circuits from the current launchingdevice to casing or current leakage from the well string into the casingformation along the well. Another method further comprises applying theelectrically insulating material around one or more portions of the wellstring immediately above or below the current launching device orreceiver. In another, applying the electrically insulating materialaround the one or more portions of the well string comprises applying atleast one of an electrically insulating swellable material; anelectrically insulating injection-molded coating; an electricallyinsulating spray coating; or an electrically insulating anodized layer.In yet another, applying the electrically insulating material around theone or more portions of the well string comprises determining a lengthof an electrically conductive portion of the formation along the well;and applying the electrically insulating material based upon thedetermined length.

The foregoing disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed. Further, spatiallyrelative terms, such as “beneath,” “below,” “lower,” “above,” “upper”and the like, may be used herein for ease of description to describe oneelement or feature's relationship to another element(s) or feature(s) asillustrated in the figures. The spatially relative terms are intended toencompass different orientations of the apparatus in use or operation inaddition to the orientation depicted in the figures. For example, if theapparatus in the figures is turned over, elements described as being“below” or “beneath” other elements or features would then be oriented“above” the other elements or features. Thus, the exemplary term “below”can encompass both an orientation of above and below. The apparatus maybe otherwise oriented (rotated 90 degrees or at other orientations) andthe spatially relative descriptors used herein may likewise beinterpreted accordingly.

Although various embodiments and methodologies have been shown anddescribed, the invention is not limited to such embodiments andmethodologies and will be understood to include all modifications andvariations as would be apparent to one ordinarily skilled in the arthaving the benefit of this disclosure. For example, one or morerepeaters may also form part of the telemetry systems described hereinand, in such cases, the same inventive principles would be applicable,as will be understood by those same ordinarily skilled persons.Therefore, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the intention isto cover all modifications, equivalents and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

What is claimed is:
 1. A method for utilizing an electromagnetictelemetry system in a downhole well, the method comprising: providing awell string comprising one or more tubulars attached to a bottom holeassembly, the bottom hole assembly comprising at least one of anelectrical current launching device or a receiver; applying electricallyinsulating material around one or more portions of the well string;deploying the bottom hole assembly into the well; conducting anelectromagnetic telemetry operation using the bottom hole assembly; andutilizing the electrically insulating material to reduce at least oneof: short circuits from the current launching device to casing; orcurrent leakage from the well string into the casing or formation alongthe well.
 2. A method as defined in claim 1, further comprising applyingthe electrically insulating material around one or more portions of thewell string immediately above or below the current launching device orreceiver.
 3. A method as defined in claim 1, wherein applying theelectrically insulating material around the one or more portions of thewell string comprises wrapping the one or more portions of the wellstring with one or more sheets of electrically insulating material.
 4. Amethod as defined in claim 1, wherein applying the electricallyinsulating material around the one or more portions of the well stringcomprises positioning an insulation sleeve around the one or moreportions of the well string, the insulation sleeve being comprised ofelectrically insulating swellable material.
 5. A method as defined inclaim 1, wherein applying the electrically insulating material aroundthe one or more portions of the well string comprises applying at leastone of: an electrically insulating swellable material; an electricallyinsulating injection-molded coating; an electrically insulating spraycoating; or an electrically insulating anodized layer.
 6. A method asdefined in claim 1, wherein applying the electrically insulatingmaterial around the one or more portions of the well string comprises:determining a length of an electrically conductive portion of theformation along the well; and applying the electrically insulatingmaterial based upon the determined length.
 7. An electromagnetictelemetry system for use in a downhole well, the system comprising: awell string comprising one or more tubulars attached to a bottom holeassembly, the bottom hole assembly comprising at least one of anelectrical current launching device or a receiver; and electricallyinsulating material positioned around one or more portions of the wellstring to reduce at least one of: short circuits from the currentlaunching device to casing; or current leakage from the well string intothe casing or formation along the well.
 8. A system as defined in claim7, wherein the electrically insulating material is positionedimmediately above or below the current launching device or receiver. 9.A system as defined in claim 7, wherein the electrical current launchingdevice is a gap sub assembly or a toroid.
 10. A system as defined inclaim 7, wherein the receiver is a gap sub assembly or a toroid.
 11. Asystem as defined in claim 7, wherein the electrically insulatingmaterial is one or more sheets of electrically insulating material. 12.A system as defined in claim 7, wherein the electrically insulatingmaterial is an insulation sleeve.
 13. A system as defined in claim 7,wherein the electrically insulating material is at least one of: anelectrically insulating swellable material; an electrically insulatinginjection-molded coating; an electrically insulating spray coating; oran electrically insulating anodized layer.
 14. A method for utilizing anelectromagnetic telemetry system in a downhole well, the methodcomprising: applying electrically insulating material around one or moreportions of a well string comprising at least one of an electricalcurrent launching device or a receiver; deploying the well string intothe well; and utilizing the electrically insulating material to reduceat least one of: short circuits from the current launching device tocasing; or current leakage from the well string into the casing orformation along the well.
 15. A method as defined in claim 14, furthercomprising applying the electrically insulating material around one ormore portions of the well string immediately above or below the currentlaunching device or receiver.
 16. A method as defined in claim 14,wherein applying the electrically insulating material around the one ormore portions of the well string comprises applying at least one of: anelectrically insulating swellable material; an electrically insulatinginjection-molded coating; an electrically insulating spray coating; oran electrically insulating anodized layer.
 17. A method as defined inclaim 14, wherein applying the electrically insulating material aroundthe one or more portions of the well string comprises: determining alength of an electrically conductive portion of the formation along thewell; and applying the electrically insulating material based upon thedetermined length.